Photographic camera with liquid-crystal diaphragm arrangement

Abstract

A photographic camera includes a diaphragm arrangement comprised of at least one body of liquid crystal positioned in the path of light entering the camera. The size of the opening of the diaphragm arrangement is changed by changing the transparency of at least one portion of the one or more bodies of liquid crystal.

1.  In a photographic camera, a diaphragm arrangement comprising liquid crystal material positioned in the path of light entering the camera, and means for changing the size of the opening of the diaphragm arrangement by alternatively changing the transparency of one or both of at least two portions of the liquid crystal material, the relative positions of said portions being such that when both said portions are non-transparent and viewed in the direction of light entering the camera said portions together form and present to such light an uninterrupted non-transparent zone, and such that when both said portions are transparent and viewed in the direction of light entering the camera said portions together form and present to such light an uninterrupted transparent zone. 
     
     
       2. A camera as defined in claim 1, wherein said diaphragm arrangement comprises a plurality of bodies of liquid crystal material positioned in the path of light entering the camera, and wherein said means for changing comprises means for changing the size of the opening of the diaphragm arrangement by changing the transparency of at least portions of said plurality of bodies of liquid crystal material. 
     
     
       3. A camera as defined in claim 2, wherein adjoining ones of said portions are located on different ones of said bodies. 
     
     
       4. A camera as defined in claim 1, wherein said diaphragm arrangement comprises an annular body of liquid crystal material, an inner annular electrode concentric with and having a diameter corresponding to the smallest aperture size of the diaphragm arrangement, an outer annular electrode concentric with and having a diameter corresponding to the largest aperture size of the diaphragm arrangement, and a circular transparent electrode bounding one side of said annular body of liquid crystal material, and having surface resistance. 
     
     
       5. A camera as defined in claim 1, wherein said means for changing comprises a light dependent voltage divider having a plurality of voltage-divider taps, a plurality of voltage threshold detector circuits each having an input connected to a respective one of said taps and each having an output, and means connecting the outputs of said voltage threshold detector circuits to different respective ones of said portions and operative for changing the transparency of different respective ones of said portions in dependence upon the signal at the output of the respective voltage threshold detector circuit. 
     
     
       6. A camera as defined in claim 4, wherein said means for changing comprises a bridge circuit including in one of its branches a light-dependent element, a difference amplifier having an input connected across the output of said bridge circuit and having an output connected to said electrode for controlling the transparency of different ones of said portions. 
     
     
       7. A camera as defined in claim 1, wherein said diaphragm arrangement comprises a plurality of bodies of liquid crystal material positioned one behind the other in the path of light entering the camera, and wherein said at least two portions are located on different ones of said bodies. 
     
     
       8. A camera as defined in claim 7, wherein said at least two portions overlap each other. 
     
     
       9. In a photographic camera, a diaphragm arrangement comprising liquid crystal material positioned in the path of light entering the camera, and means for changing the size of the opening of the diaphragm arrangement by changing the transparency of at least a portion of the liquid crystal material, said means comprising two transparent electrodes positioned in the path of light entering the camera respectively in front of and in back of the liquid crystal material, one of said transparent electrodes having surface resistance, electrical circuit means operative for establishing between two spaced locations on said one of said electrodes a variable potential difference, thereby causing the potential difference between either one of said spaced locations and locations on said one of said electrodes intermediate said spaced locations to have a value dependent upon the distance from said spaced locations, and additional electrical circuit means operative for maintaining the different portions of the other transparent electrode at a potential such that a continuous change in said potential difference will result in a continuous change in the potential difference between corresponding locations on the two transparent electrodes and accordingly a continuous change in the size of the nontransparent portion of the liquid crystal material intermediate the transparent electrodes. 
     
     
       10. In a photographic camera, a diaphragm arrangement comprising liquid crystal material positioned in the path of light entering the camera, and means for changing the size of the opening of the diaphragm arrangement by alternatively changing the transparency of one or both of at least two portions of the liquid crystal material, the relative positions of said portions being such that when both are non-transparent light is blocked from passing between them and that when both are transparent there is between them no obstruction to the passage of light, wherein said means comprises two transparent electrodes positioned in the path of light entering the camera respectively in front of and in back of the liquid crystal material, one of said transparent electrodes having surface resistance, electrical circuit means operative for establishing between two spaced locations on said one of said electrodes a variable potential difference, thereby causing the potential difference between either one of said spaced locations and locations on said one of said electrodes intermediate said spaced locations to have a value dependent upon the distance from said spaced locations, and additional electrical circuit means operative for maintaining the different portions of the other transparent electrode at a potential such that a continuous change in said potential difference will result in a continuous change in the potential difference between corresponding locations on the two transparent electrodes and accordingly a continuous change in the size of the non-transparent portion of the liquid crystal material intermediate the transparent electrodes.